The present invention relates to a method and system for monitoring whether multiplex equipment operates normally or not.
In the monitor system for the multiplex equipment known heretofore, input and output signals of the multiplex equipment are branched to be inputted to a monitor system for detecting the presence or absence of a discrepancy between these signals by checking through comparison, wherein decision is made that the monitor system suffers a fault only when the discrepancy is not detected in all the comparisons performed on the channel basis of the low speed signal group, as is disclosed in an article entitled "Multiplex Equipment IN-OUT CHECK in the national conference (1979) of The Institute of Electronics And Communication Engineers of Japan", Article No. 203.
In the prior art system mentioned above, no consideration is paid to the time taken for making a decision of occurrence of fault or trouble after detection of discrepancy in the comparison, presenting thus a problem that a lot of time is involved for making a decision of the presence of a fault after detection thereof.
More specifically, in the case of the system known heretofore, monitoring of the multiplex unit is performed for each of the channels (i.e. on a channel basis) in the order of channel sequence of the low speed group signal, being followed by the monitoring of the demultiplexing unit on a channel basis in accordance with the channel sequence of the low speed group signal in a similar manner, whereupon the monitoring of the multiplex unit is again repeated. Such processing sequence is not changed at the time when discrepancy in the comparison is detected for the first time. Further, when comparison for all the channels of the low speed group signal results in discrepancy, the situation may be considered as being ascribable to the fault of the comparator or comparison procedure. Accordingly, the first detection of discrepancy in the comparison is not allowed to deduce the decision that the equipment suffers a fault. In other words, the fault of equipment can not be decided until no discrepancy has been detected in a certain comparison. Thus, a lot of time is required for making decision of the presence of fault from the detection of discrepancy in the comparison. By way of example, let's suppose that in a multiplex equipment for multiplexing and demultiplexing low speed group signals of n channels, a fault occurs in a high speed group processing circuitry of the multiplexing unit and that discrepancy in the comparison is already detected in the comparison for the first channel. In that case, discrepancy will also be detected in the comparison for the second to n-th channels due to the fault in the high speed group signal processing circuitry. Thus, no discrepancy will be detected at length only in the comparison for the first channel in the monitoring of the demultiplexing unit. In other words, the fault of equipment is allowed to be decided only at this time point.